Claims that restoring the Nomadic ship could cost the taxpayer £7 million were today denied by the government.
The Belfast-built vessel carried passengers to the Titanic in 1912 and is moored in the city, receiving a makeover.
Stormont's Public Accounts Committee (PAC) claimed the project could leave the public footing the £7 million bill. It blamed Government inexperience for the extent of unforeseen costs like transportation and assistance to the trust behind the overhaul - which paid consultants £60,000 a year.
A spokesman for the Department for Social Development said most of the money would come from Europe.
PAC chairman Paul Maskey said: "The committee recognises that the trust is a voluntary organisation staffed mainly by part-time workers and enthusiasts who were keen to see progress on the ship.
"However, these are challenging times. Preserving our heritage is important but not at any cost."
The historic boat was purchased by the Department for Social Development for £263,000 in 2006.
Up to December 2008 the department had spent £650,000 on transportation, essential restoration and financial assistance to the SS Nomadic Charitable Trust.
The department told the committee it would not fund the costs of restoration, that was a matter for the trust, which has secured £3.6 million towards the cost of restoration. However more than 90% of this has come from public funds.
According to the PAC, the department currently estimates the cost of restoring the Nomadic to be in the range of £5 million to £7 million.
A more accurate estimate will be provided by a conservation management plan being prepared for the trust.
Until this is finalised only essential restorative work will be undertaken.
The 37-page report, Bringing The SS Nomadic to Belfast - The Acquisition And Restoration Of The SS Nomadic, said: "In purchasing the Nomadic, the department acknowledges that it was getting involved in areas in which it had very little experience.
"That is evident by the significant additional costs incurred by the department since the Nomadic was purchased and the delays in finalising the conservation management plan and raising the necessary funds for its restoration.
"The delays in progressing the project also increase the risk of reputational damage to both the department and trust should the Nomadic not be fully open to the public at the time of the centenary celebrations of the launch of the Titanic in 2011."
The committee recommended that the department and trust must work together to ensure that contractors are appointed to enable work to commence at the earliest opportunity.
"It is critical to get the ship to a stage where it is open for viewing by the paying public who will then be contributing to its restoration costs and ongoing maintenance, thus reducing the burden on the public purse," the report added.
A spokesman for the DSD said they would respond shortly to the report.
"There is no question of the Northern Ireland taxpayer paying £7 million to fund the Nomadic," he said.
"The majority of this money will come from European funding and heritage lottery funding."